<ul class="nav nav-sidebar">
    <li id="announcement-list"><a href="{% url 'announcement-list' %}">公告-列表</a></li>
    <li id="announcement-add"><a href="{% url 'announcement-add' %}">公告-添加</a></li>
    <li id="announcement-update"><a href="{% url 'announcement-list' %}">公告-更新</a></li>
</ul>